1. Field of the Invention
The present invention relates to an improved low pressure discharge lamp having a nonlinear arc path formed by a partition placed in the lamp envelope.
2. Description of the Prior Art
Various attempts have been made to improve lighting fixtures because of strong demand of saving energy. Incandescent lamps have also been a target for the improvement. For example, a high efficient fluorescent lamp is miniaturized and is substituted for a low efficient incandescent lamp.
An approach for miniaturizing the fluorescent lamp is to form a series of multi-bent path by a partition (6) in a cylindrical lamp envelope (2) to provide the longest arc path in a limited space in the lamp envelope.
Use of the partition (6) provides effectively a long arc path in the limited space and is one of the most desirable ways for fabricating a small sized fluorescent lamp instead of the incandescent lamp.
In the conventional fluorescent lamp having a partition, a circular glass envelope or a spherical glass envelope has been used as a lamp envelope (2). It is necessary to employ a hermetically sealing or a special method for fixing the partition made of glass or metal plate. This causes the following disadvantages: it takes much time for fabricating the lamp; the sealed portion is visible from the outside because application of phosphor on the sealed portion is impossible; when the phosphor peels off from the connecting part of the partition (6) in the lamp envelope (2), a transparent portion appears in the lamp; and the resulting phosphorlost part becomes large due to the vibration during transportation.